In my case I began with the 17-55 (paired with a 70-200)... and later bought a 24-105 as an all purpose lens when I didn't want to switch.

But I'm thinking of selling te 24-105 now as I end up returning to the 17-55, despite its limited reach. I tend to shoot interviews wide open, and really appreciated the extra stop (for tighter DOF in standard focal length shots). If anything, I feel the 17-55 IQ is superior (it's an L in this regard as others routinely report), and I've never had any issues with build quality / dust.

As Daniel mentioned, it is a tad annoying that the 17-55's focus ring is narrower and falls in a non-standard position relative to the zoom ring.

I love the 24-105 a lot. Its my go to lens on the C300 for interviews. I set the shot for a tight at 105mm and then zoom out for my medium/wides. The 24-105 is parfocal. Well I guess it's hard to confirm but I have had great success with it. You just have to make sure you set focus at 105mm then pull out. Works very well for me. I think it's a must own lens due to the range as well as the sharpness.

For you guys that have the 24-105 f4, do you miss the shallow depth of field on the c100? I can assume that on the longer range, throwing backgrounds out of focus is not an issue, but what about on the wider end?

Doing a rough an 'eyeballing' sort of comparison (I'm just finishing off an edit from a job I've been doing since 2004 'back in the day' of the DSR-570, so I can compare a few standard shots), I'd have said the 24-105 was on the improved side of working with a 2/3" camera wide open on a standard ENG lens.

FWIW, I did a comparison with an S35 lens at f8 compared to an EX1R's built-in lens (half inch chip) at f2.8, and again the S35 lens was a tad shallower. At f8.

I've still got 1.4 35mm and 50mm lenses, and the 2.8 17-55, so if I need wafer-thin DoF, they're in the bag.

I agree that it's good to have low-light and shallow dof when you need it, and deep focus when you need it. One question I've always wondered though, with both still and video, is whether a big sensor is necessarily a net gain in terms of "raw" image quality.

Say you for whatever reason must match the dof between the EX1 and the C100, how far must you stop down your lens on the latter for any given equivalent focal length? And by the time you stop so far down, will the image actually become "worse" than the EX1's because by that time you will have had turned up the gain so much?

Of course in practice there're too many variables to allow generalization. Matt's already posted about how EX1 resolves lines more than FS100. But what I mean is, if somehow we could isolate only sensor size and aperture/dof and "raw" image quality, "all other things being constant" as they say in science.

So the EX1R came 'on song' at f4, happy at f5.6, began to look a little jaded by f8. PD150/Z1 at 1/3" happy at about 1/3 stop less than that. S35 lenses on C100 are sort of kosher to f11, running out of steam by f16, but very happy at f8. Seeing a pattern here.

For you guys that have the 24-105 f4, do you miss the shallow depth of field on the c100? I can assume that on the longer range, throwing backgrounds out of focus is not an issue, but what about on the wider end?

If I'm shooting an interview the I would be at around 50mm to 85mm range at f4. I like it when the subject IS in focus. The whole subject. Including their ears. If you shoot at 1.4 or 2.0 and your subject moves a little then they go out of focus. Not good. The background is plenty defocused at least for my taste. Razor thin DOF can be distracting as much as it is cool.

I'm looking for a camera upgrade, and with the 1000k price drop, the c100 really interests me. Question on purchasing a zoom lens: I need a zoom lens to zoom in and out while recording, like on my video camcorders that have a zoom rocker, or that I can connect a lanc varizoom. Is there a zoom lens that someone can recommend? I shoot plays and concerts that require me to consistantely zoom in and out on the fly.